Pressure switch



PRESSURE SWITCH Nov. 6, 1934.

, 1934 2 Shees-Sheeil l Jan.

EE.L

s. R. DU BRIE 1,979,608

PRESSURE SWITCH Nov. 6, 1934.

2 Sheets-Sheet 2 Filed Jn. 11, 1954 Patented Nov. 6, 1934 UNITED STATES PATENT OFFICE This invention relates to pressure switches and more particularly to pressure switches of the generic class exemplified by the one shown in the patent to Kyser, 1,447,729, of March 6, 1923.

In that patent, there is shown a pressure switch provided with a. pressure responsive diaphragm which controls the position of a bell crank in turn connected to a movable circuit closing contact through a quick make and break mechanism. l

l@ One of the principal objects of the present invention is to provide a novel quick make and break mechanism whereby the bell crank will actuate the movable circuit closing contact in a novel and efficient manner.

l5 A further object of the present invention is to provide one of the elements of the quick make and break mechanism that connects the movable contact to the bell crank with an adjustment means for permitting the operating range of the 2@ switch to be varied. Pressure switches of this character are arranged to cut in or make contact at a pre-determined low pressure, and to cut out or break contact at a pre-determined high pressure. There have previously been provided adjustment means which make it possible to shift the operating range bodily, but there has not yet been provided an adjustment means which makes it possible to widen or narrow the operating range.

A further object of the present invention is to provide a novel contact arrangemenhfar more satisfactory for use in switches in general and pressure switches in particular, than heretofore known contacts.

A still further object is to provide in a pressure switch a novel form of indicator to indicate the pressure ein'sting in the pressure chamber, the indicator being operatively independent of the make and break mechanism so as not to be affected by quick make or quick break of the contacts.

di@ Other objects of the invention will presently appear upon reference to the following description of an embodiment, shown in the appended drawings. 1n these drawings,

Fig. 1 is a rear elevation view of the switch,

with the rear cover removed;

Fig. 2 is a fragmentary section as if on line 2--2 of Fig. l, with the rear cover in place, but with other parts not shown, for purposes of clarity;

5G Fig. 3 is a side elevational view of the contact mechanism;

Fig. 4 is a diagrammatic front View of the switch, particularly showing the operation of the indicator and the make and break parts.

Referring to the drawings for an understanding of the invention, it will be seen that the switch therein shown comprises a base plate l0 and a casing l1 having sides 11a, a front wall 1lb, and a top llc. Under the base plate, which is circular in form but which has diametrically opposed extensions 12 vprojecting from the circle thereof is a circular diaphragm 14 of heavy rubber or the like and immediately under this diaphragm is a chambered diaphragm plate 15. The base plate, the diaphragm, and the diaphragm plate are relatively secured in assembly to provide a pressure chamber of the character so well known in pressure switches by means of the series of bolts 16. Two other bolts, referenced 17, are passed through the extensions 12 of the base plate and into bosses 18 of the casing walls 11a to secure the casing to the base plate, and thus to secure the casing and the pressure chamber in assembly.

Disposed within the pressure chamber and above the diaphragm is a pressure plate (not shown) provided with an upwardly extending pin 20 engaging the horizontal arm 2l of the pressure bell crank 22, the latter being pivoted at 23 to bosses 23a formed integral with the base plate l0. The vertical arm 24 of the bell crank projects upwardly in the casing to a point adjacent the top llc thereof, and the upper end of the vertical arm 24 is connected to the side wall 11a of the casing by a coiled tension spring 25 and an adjustable bolt 26.

It is observed that an increase ofrpressure in the pressure chamber tends to move the pressure bell crank 22 clockwise on its pivot 23, Fig. l, against the iniuence of the spring 25, and that a decrease in pressure of the pressure chamber permits the spring 25 to pull the bell crank 22 counterclockwise, Fig. l.

The operating mechanism of the switch, as a whole, is connected to the vertical arm 24 of the hell crank at the oating pivot point 28, through the medium of a link 29 which in turn is connected at 30 to the upper end of the vertical arm 30a of a T-shaped crank 31 which is journaled on a xed pivot in the form of a pin 32 secured to the casing wall 11b, the pin 32 passing through a huh 32a at the intersection of the two arms of the T-shaped bell crank, one of these arms being the arm 30a heretofore mentioned, and the other being the arm that is referenced 33-34. This arm, which is more properly the switching arm, comprises two parts :S3- 34, adiustably interconnected through the medium of the screw 35 disposed in the aligned slots 36 of the two parts 33-34, this construction providing an adjustment means whereby the length of the arm 33-34 may be increased or decreased to widen or narrow the operating range for the switch, by raising or lowering the critical switch opening and closing pressures.

On the end of arm 33-34 is a pin 37, and coiled tension spring 39, which forms an overcenter spring for the quick make and break or snap mechanism, has one end hooked around the pin 37. The other end of this spring is hooked around a pin 40 projecting from the arm 41 of a bell crank 42, the latter being journalled at its elbow on a fixed pivot 43 in the form of Aa bolt threaded into the front wall of the casing 1l. The vertical arm 44 of the bell crank 42 has at its lower end a hole through which passes a rod 45 of insulating material such as fiber or the like, and on the opposite ends of this rod are disposed metallic sleeves 46 which form the movable contacts of the contact mechanism and which engage the stationary spring contacts 47 mounted on the insulating block 48 disposed against the side Wall 11a of the casing 11.l The block 48 and its supplementary block 49, also of insulation, are held in place by the screws 50 which mount the contacts 47, these screws projecting through the casing wall to form externally accessible binding posts upon which are threaded binding nuts 5l.

It will be observed that when the pressure bell crank 22 rocks clockwise (Fig. l) on an increase in pressure, the T-shaped bell crank 3l will rock clockwise on its fixed pivot 32 until the arm 33-34 and coil spring 39 move overcenter with respect to the pin 40, and the fixed pivot 43 of the bell crank 42. Such movement causes the Ybell crank 42 to move for quick break, from the position shown, counterclockwise on its xed pivot 43 and move the contact sleeves 46 out of contact making position and from the stationary contacts 47. Conversely, a decrease in pressure will cause the switch to close, if it had been opened, the overcenter arrangement providing quick make movement for the parts.

The Contact arrangement Inasmuch as the speciiic form of contacts herein used form an important object of the invention, the contacts will be described specifically. The movable contact has already been described as comprising a rod 45 of suitable insulating material such as fiber, upon whose ends are metallic sleeves` 46. 'I'he stationary contacts, of which there is a pair for each sleeve 46, or four contacts in all, comprise copper spring members bent to the formation shown in Fig. 1, each contact including a base portion 47a, leg 47h, and a spring leaf 47C, the leaves of adjacent contacts being directed towards each other and being formed to have a constant tendency to approach each other, so as to narrow the distance between the leaves of adjacent contacts.

It will be observed that when the movable contacts 46 are moved towards the stationary contacts 47 for circuit closing, they will have a cornpound movement which may be described as rotary (about the fixed pivot 43) and sliding or wiping. Accordingly, as the movable contact sleeves 46 engage the leaves 47e of the stationary contacts 47, they roll on them,`as well as slide along these leaves. This compound movement is found to be more satisfactory for contact making than a simple sliding movement.

The indicator In order to show accurately the pressure existent within the pressure chamber, there is provided an indicator means which will now be described. Cut in the front wall 11b of the casing 11 is a window 54 (Fig. 4) through which may be Viewed the pressure indicating numbers marked on the front surface of an indicator plate 55, the latter being a thin arcuately shaped metal plate positioned to slide and rotate along and against the back surface of the front wall 1lb of the casing, the plate, however, being within the casing. The plate has an integral radial arm 56 which is journalled on a fixed pivot 57, in the nature of a pin threaded into the front wall of the casing, and the lower end of the arm, referenced 58, is connected by a link 59 to the oating pivot 60 at the lower end of the vertical arm 30a of the T-shaped bell crank 3l.

It will be observed that when the pressure bell crank 22 rocks to the right, Fig. 1, on an increase in pressure, that the link 59 will move to the left, and that indicator plate will rotate clockwise about its fixed pivot 57 so that its pressure numbers will successively be viewed through the window 54, thus properly indicating the pressure in the pressure chamber as translated through the position of the pressure bell crank 22.

It will also be observed that the indicator reading is accurate inasmuch as it is dependent upon the pressure within the chamber and is not in any way affected by the quick make and break parts.

The switch here shown in its entirety, and due to the provision of the novel quick make and break parts, the novel contacts, the novel adjustment means for the arm 33-34 of the make and break bell crank 31, and the novel indicator, is a satisfactory switch, and one that can be manufactured economically and utilized eniciently.

Now having described a preferred embodiment of the invention, selected only for purposes of illustration and not to be considered as exhausting the possibilities of the invention, reference will be hadto the appended claim which determines the scope of the invention herein described.

I claim:

In a switch, a movable Contact set, including a rotating arm, a rod of insulation carried thereby and disposed perpendicularly thereto and parallel to the axis of rotation thereof, the arm being connected to the rod at the central point of the latter. separate and independent metal sleeves on said rod, and separate and independent stationary contact sets, each including separated stationary retroverted U shaped spring contacts having a space therebetween, and means for rotating said arm and thus causing each sleeve to advance into each space with arotary sliding motion, and to spring apart said contacts.

-STANLEY R. DU BRIE. 

